This invention relates generally to energy metering, and more particularly, to solid-state electricity metering.
Electricity meters are utilized to measure energy usage. Such meters must be reliable, cost-effective and accurate. In addition, it is desirable for a meter to be configurable so that functionality can be added to or removed from the meter, as needed.
Metering energy consumption by loads coupled to a single phase of a power line, such as residences, typically is performed by a mechanical meter including a disk which rotates at a rate related to energy consumption. A mechanical register is driven by the disk. Specifically, the mechanical register includes gears and a display. The gears are coupled to and driven by the disk, and the gears drive the display. Kilowatt-hour consumption is indicated on the display.
Such mechanical meters are extremely reliable and cost effective. Mechanical meters, however, typically display limited data, e.g., only watt-hour consumption, and are not configurable, e.g., functionality is not easily added to such meters when installed in the field.
Meters that include electronic registers typically are utilized for metering energy consumption by commercial and small industrial loads and in some residential applications. The electronic registers measure energy consumption as well as other values useful in billing, such as demand and time-of-day usage. Such meters include a disk which rotates at a rate related to energy consumption, and an optical assembly that generates electric pulses at a rate proportional to the rate of rotation of the disk. The pulses are provided to the electronic register for making energy consumption calculations. Such a meter typically is referred to as an electro-mechanical meter since the metering function is performed using a mechanical disk and the register function is performed by an electronic register.
Electro-mechanical meters provide more processing capability and metering quantities than mechanical meters. Electro-mechanical meters also are more flexible in that functionality can be added to or removed from the meter. For example, electronic demand registers and a time-of-use registers are fabricated as separate, interchangeable modules that can be secured within the meter enclosure depending upon the desired functionality.
Meters that perform both the metering and register functions using electronics, i.e., no rotating disk, sometimes are referred to as solid state meters. Such meters are more expensive to fabricate than mechanical meters, and therefore, typically are only utilized in high energy usage applications, e.g., only for industrial sites.
It would be desirable to provide a solid state residential meter that is not only reliable and accurate, but also cost competitive with single phase mechanical meters. It also would be desirable to provide such a residential meter that is flexible in that the meter functionality can be upgraded and downgraded in the field without a need to remove the meter from the installation. In order to install additional or different functions, however, it may be necessary to reprogram a processor in the meter. Reprogramming may require disassembling the meter and removing the processor to be reprogrammed and may even require the meter to be removed from the installation.
A method is described below for reprogramming a meter without a need to disassemble it or remove it from the installation. In one embodiment, the method includes configuring the meter to accept user code reprogramming at meter power-up and, at power-up, providing user code reprogramming to the meter control program. The meter is configured to accept user code at power-up by executing processor boot loader code providing for optional loading of user code into the processor memory upon processor boot-up.
The above-described method allows a user to reprogram the meter processor easily and quickly. The meter user thus can add or change metering functions and options without disassembling the meter or removing it from service.